Update vnodeQueryImpl.c

fix a bug referred in issue #946

src/system/detail/src/vnodeQueryImpl.c

@@ -1349,11 +1349,12 @@ static int32_t blockwiseApplyAllFunctions(SQueryRuntimeEnv *pRuntimeEnv, int32_t
  *
  * first filter the data block according to the value filter condition, then, if the top/bottom query applied,
  * invoke the filter function to decide if the data block need to be accessed or not.
+ * TODO handle the whole data block is NULL situation
  * @param pQuery
  * @param pField
  * @return
  */
-static bool needToLoadDataBlock(SQuery *pQuery, SField *pField, SQLFunctionCtx *pCtx) {
+static bool needToLoadDataBlock(SQuery *pQuery, SField *pField, SQLFunctionCtx *pCtx, int32_t numOfTotalPoints) {
   if (pField == NULL) {
     return false;  // no need to load data
   }
@@ -1371,6 +1372,11 @@ static bool needToLoadDataBlock(SQuery *pQuery, SField *pField, SQLFunctionCtx *
     if (!vnodeSupportPrefilter(pFilterInfo->info.data.type)) {
       continue;
     }
+    
+    // all points in current column are NULL, no need to check its boundary value
+    if (pField[colIndex].numOfNullPoints == numOfTotalPoints) {
+      continue;
+    }
 
     if (pFilterInfo->info.data.type == TSDB_DATA_TYPE_FLOAT) {
       float minval = *(double *)(&pField[colIndex].min);
@@ -6595,7 +6601,7 @@ int32_t LoadDatablockOnDemand(SCompBlock *pBlock, SField **pFields, uint8_t *blk
        * filter the data block according to the value filter condition.
        * no need to load the data block, continue for next block
        */
-      if (!needToLoadDataBlock(pQuery, *pFields, pRuntimeEnv->pCtx)) {
+      if (!needToLoadDataBlock(pQuery, *pFields, pRuntimeEnv->pCtx, pBlock->numOfPoints)) {
 #if defined(_DEBUG_VIEW)
         dTrace("QInfo:%p fileId:%d, slot:%d, block discarded by per-filter, ", GET_QINFO_ADDR(pQuery), pQuery->fileId,
                pQuery->slot);